The Japanese Patent Application, first publication, No. Sho 61-208247 discloses an electronic apparatus having a conventional mounting structure. The electronic apparatus comprises a flat-pack IC and a printed circuit board. The flat-pack IC has a plurality of terminal leads protruding horizontally from a body of the flat-pack IC, and alignment leads formed by bending several terminal leads at right angles. The printed circuit board has a plurality of terminal pads for establishing an electrical connection and alignment holes for receiving the alignment leads. The terminal pads are made on the upper surface of the printed circuit board, corresponding to the terminal leads of the flat-pack IC, and the alignment holes corresponds to the alignment leads of flat-pack IC. In the mounting structure of the electronic apparatus, by inserting the alignment leads of the flat-pack IC into the alignment holes on the printed circuit board, the terminal leads are properly aligned with the corresponding terminal pads.
When surface mounting electronic devices are mounted on both surfaces of the printed circuit board, a first electronic device is soldered on one surface, and a second electronic device is thereafter soldered on the underside. In the process of soldering the second electronic device, the board is turned over so that the first electronic device is positioned on the underside of the board.
However, when a heat radiating device is disposed on the upper side, corresponding to the first electronic device on the underside, the first electronic device may accidentally fall from the board, because the solder bonding the first electronic device melts due to the heat to solder the second electronic device and cannot support the weight of the first electronic device. In addition, the same problem occurs when the second electronic device is replaced, because the board is heated in order to remove the second electronic device.